United's capitulation began six minutes after the restart following a goalless opening 45 minutes.

An unmarked Nacho Monreal volleyed home directly from a corner to give Arsenal a 51st minute lead, before Marko Arnautovic became the first Hammers to score ten goals in a season since Diafra Sakho three years ago with a great strike across the face of Arsenal 'keeper David Ospina.

But three goals in the space of just seven minutes were more than enough to secure all three points for the hosts. A 82nd minute Declan Rice error allowed Aaron Ramsey's centre to find its way into the net, before the game was all but wrapped up when Alexandre Lacazette beat Joe Hart low to his left hand side.

But there was still time for a fourth as former West Ham target Lacazette slotted home his second of the day in the final minute of normal time to give the final score a somewhat flattering appearance.

The defeat resulted in West Ham dropping a palce to 15th in the Premier Leaguem, behind Crystal Palace on goal difference. David Moyes' side remain six points clear of the relegation zone, with four games left to play.